This invention relates to a coupling between a plurality of rotatable members of generally circular cross section. More particularly in one form, it relates to a coupling between aligned, co-operating members of a shaft.
In rotating apparatus, for example shafts, drums, etc. in power generation machinery such as a turbine engine, it can be desirable to join cooperating, rotating members of dissimilar materials, metals or alloys. Examples of such rotating members include shafts, drums, conical structures, etc., designed in various forms within a gas turbine engine. A variety of reported methods for bonding such dissimilar metals and alloys include diffusion bonding, conventional welding, friction welding, brazing, and explosive bonding, depending on such conditions as the intended operating temperature of a component being formed and the mechanical properties required in the joint between such members. When significant differences exist in properties, such as in strength, thermal expansion, etc., transition metals or metal alloys have been bonded between members.
In modern gas turbine engines, it can be beneficial, for example for weight reduction, to use for a rotating component, such as a shaft, a combination of a metal or metal alloy member and a fiber-reinforced member, such as a metal matrix composite, carried together for rotation. One example of such a composite known in the art includes a matrix based on Ti or an alloy of Ti, reinforced with fibers, for example glass, graphite, carbon, polymer, metal, etc. Bonding, such as the types identified above, does not provide adequate mechanical and/or physical properties to a joint between such members of significant differences in thermal expansion characteristics. Such bonding particularly is a problem when it is intended to transfer torque between such cooperating, dissimilar members during rotation.
The present invention, in one embodiment, provides a mechanical coupling to transfer torque between cooperating rotatable members, each of substantially circular cross section and aligned along an axis of rotation. The coupling as a combination comprises a first member having a first surface portion of a fiber reinforced composite material including fibers oriented predominantly within about 45xc2x0, on either side, of the axis of rotation. The first surface portion includes a first plurality of spaced-apart teeth projecting from the first surface portion, in one form generally axially and disposed generally circumferentially about the first member.
The coupling comprises a second member having a second surface portion including a second plurality of spaced-apart teeth projecting from the second surface portion toward the first plurality of teeth, in one form generally axially and disposed generally circumferentially about the second member. The first and second plurality of teeth cooperate in juxtaposition to interlock one with the other defining an interface between the first and second members. Clamping means holds the first and second members together at the interface.